OKO 30mm tuning

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Madass140

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New here so dont be to hard on me, if there is an OKO tuning thread, moderators please move my post there, Not Mini but of more importance is the tuning of my 30mm OKO.
Engine is a Chinese Honda based CG125, mods are, 150cc, 1mm bigger valves 25mm x 30mm, big cam, ported head, opened up pipe and 30mm OKO.
been playing with the settings and the best so far is needle in bottom groove, 42 pilot,95 main, air screw 1 turn out, I've tried different settings, this is the best so far,
without any load it revs freely, but under load its a bit sluggish mid range, which way should I be going?
 

Carlts

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Best advice would be to dump the 30mm and go the 26mm, much easier to tune as the 30mm are sometimes impossible to remove the flat spot fully :(

I have a 26mm and 30mm OKO and I have managed to get the 26 tuned beautifully, but the 30mm is a handful and I am yet to be successful either. Here is some threads that might help:

http://www.miniriders.com/carby-tuning/23986-those-about-rock-buying-oko-flatslides.html

http://www.miniriders.com/carby-tuning/24570-carby-settings-your-bike.html

also a nice tuning guide:
http://tboltusa.com/store/tech.php?pID=61/Simple+Guide+to+Jetting

Good luck mate
 

Carlts

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The 26mm and 30mm have the exact same fitment, they use the same jets and even slide too. I just interchange mine while using the same manifold.

For your engine size the 26mm would be perfectand with these settings would be pretty much perfect, the most robust setup for the OKO:

Jetting specs used: #36 Pilot jet. #102 Main Jet. JJH needle
 

Madass140

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if no improveent with a bit more playing around, I'll buy a 26, I tried a 36 pilot, a 37 made a slight improvement, the 42 made the best improvement.
 

DHZ_XR8cing

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The 30mm OKO is mongrel of a carbie to tune. I find you get better performance out of the 26mm OKO.
On your engine I would suggest nothing bigger than a 38 pilot. If your going to 42 and getting it running better it could be a mixture or needle height adjusment needed.
Try a 38/98 and clip on the middle. That will give you a basic setup and a good base to work from.
Remember that when an engine is either running rich or lean it will give the same problems so be careful to not go the wrong way.

Never try tuning you bike for free revving. Its how it rides that matters. when it free revs it gets a full dose of air and fuel in 1 hit and that never happens when your riding it.

A basic rule is
if its having problems from idle to 1/4 throttle its a pilot jet problem.
1/4 to just over 1/2 throttle its a needle height problem.
Problems in the higher rev range is main jet.
Try fixing each problem separatley as it will save you chasing your tail.
 

zwebx

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heres a good explanation *got the throttle turns in relation to parts of carby*

 
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Madass140

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Well I took the advice and bought a 26mm carb, but its not an OKO its a copy called KOSO, made in Taiwan, chrome slide, looks good quality, has a Power jet unlike the OKO, it apparently only works at full throttle.
I've fitted the carb with a 38 pilot and 95 main with needle in middle position, I'll give it a try soon, any info on the KOSO carb? good or bad or whatever???
 

Madass140

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well, the best settings with the new 26 KOSO are 38/90, needle 2nd from the top, air screw 1.5 turns out.
I tried many adjustments and settings under load, I live on a steep hill, also I live 1000ft above sea level which ay account for the 90 main jet, BUT its running pretty good thru out the rev range under load , and it flies.
I think I'm getting there ,
ohh I'm now running Petron Blaze, its 100 octane, AU$1.25/litre at the at the bowser,
 

Carlts

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Great your getting somewhere, haven't seen the copies, but if it's working then go for it!!!! What type of jets does it run, hex or circle?
 

Madass140

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yep it runs the same hex jets and same slow jet, The chrome on the OKO slide is peeling off, great goin thru the motor, I'm inclined to think the KOSO carb may be a better quality unit, at least it has the Power jet.
more tuning but I'm making good headway now, it sure revs high, nothing like the stock motor it was.
the KOSO carb cost me a about $20 more, $75,
 

Madass140

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yep hex jets the same, I noticed the chrome peeling off the OKO slide, it has a very BIG cutaway also compared to the small 3.5 cutaway of the 26mm KOSO
 

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wogtaz ryder

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Just throwing it out there i loved my 30mm oko over my 26 anyday , it was a plug and play item just like the 26mm was to and had all the bottom end my 26mm had plus **** load more mid to topend ..

Off the top of my head i believe i ran the same jets in the both of them ..

Its known that theirs is even real and fake Oko's (china copying china...funny) so could be the case .
 

Carlts

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^^^ Hey Woggy, do you know the exact jetting you used and also the needle type and positioning? I am yet to have any luck
 

DHZ_XR8cing

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I think the 30mm is hit and miss. Some are ok and others can never be tuned spot on.
Carlts. When I had the Crf 70 style bike I found I had to run the bike a bit leaner compared to the LXR. I think its got to do with the design on exhaust. The lxr is less restrictive.
 

rotn50

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I had a 28mm KOSO and it worked brilliant but like most 28s it was inconsistent and no matter what i did i could not get it to idle on its own, but after reading something from 00racing where they were selling a flatslide carb they said idle will have to be around 2000 revs for max performance up to 1/4 throttle, even with my 26 OKO and now the 30mm mikuni i went back to so i could get an idea of whats happening(i.e is my prob carb, or engine setup, or bad tune) but im still having a prob from idle to 1/4 throttle just bogging and i ride trails and depend on not needing to ride the clutch to keep it running thru that range since adding the V2 and high comp piston, honestly im wondering if my engine setup and exhaust setup may require a higher idle, but back to the koso, there build quality was really good and was fairly cheaper than an oko of smaller capacity.
 

wogtaz ryder

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Would be a genuine that comes with the 143 kits..

Sorry carlts cant remember the jets i used. maybe 36 / 108 or so ? but im not positive on that.
 

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